PEP 241: Metadata for Python Software Packages
Mon, 19 Mar 2001 17:30:19 -0500
Title: Metadata for Python Software Packages
Version: $Revision: 1.6 $
Author: A.M. Kuchling <firstname.lastname@example.org>
Type: Standards Track
This PEP describes a mechanism for adding metadata to Python
packages. It includes specifics of the field names, and their
semantics and usage.
Including Metadata in Packages
The Distutils 'sdist' command will be modified to extract the
metadata fields from the arguments and write them to a file in the
generated zipfile or tarball. This file will be named PKG-INFO
and will be placed in the top directory of the source
distribution (where the README, INSTALL, and other files usually
Developers may not provide their own PKG-INFO file. The "sdist"
command will, if it detects an existing PKG-INFO file, terminate
with an appropriate error message. This should prevent confusion
caused by the PKG-INFO and setup.py files being out of sync.
The PKG-INFO file format is a single set of RFC-822 headers
parseable by the rfc822.py module. The field names listed in the
following section are used as the header names. There's no
extension mechanism in this simple format; the Catalog and Distutils
SIGs will aim at getting a more flexible format ready for Python 2.2.
This section specifies the names and semantics of each of the
supported metadata fields.
Fields marked with "(Multiple use)" may be specified multiple
times in a single PKG-INFO file. Other fields may only occur
once in a PKG-INFO file. Fields marked with "(optional)" are
not required to appear in a valid PKG-INFO file, all other
fields must be present.
Version of the file format; currently "1.0" is the only
legal value here.
Example: 'Metadata-Version: 1.0'
The name of the package.
Example: 'Name: BeagleVote'
A string containing the package's version number. This
field should be parseable by one of the Version classes
(StrictVersion or LooseVersion) in the distutils.version
Example: 'Version: 1.0a2'
Platform (multiple use)
A comma-separated list of platform specifications, summarizing
the operating systems supported by the package. The major
supported platforms are listed below, but this list is
POSIX, MacOS, Windows, BeOS, PalmOS.
Binary distributions will use the Supported-Platform field in
their metadata to specify the OS and CPU for which the binary
package was compiled. The semantics of the Supported-Platform
are not specified in this PEP.
Example: 'Platform: POSIX, Windows'
A one-line summary of what the package does.
Example: "Summary: A module for collecting votes from beagles."
A longer description of the package that can run to several
paragraphs. (Software that deals with metadata should not
assume any maximum size for this field, though one hopes that
people won't include their instruction manual as the
Example: "Description: This module collects votes from beagles\n
in order to determine their electoral wishes.\n
Do NOT try to use this module with basset hounds;
it makes them grumpy."
A list of additional keywords to be used to assist searching
for the package in a larger catalog.
Example: 'Keywords: dog puppy voting election'
A string containing the URL for the package's home page.
Example: 'Home-page: http://www.example.com/~cschultz/bvote/'
A string containing at a minimum the author's name. Contact
information can also be added, separating each line with
Example: 'Author: C. Schultz
Universal Features Syndicate
Los Angeles, CA'
A string containing the author's e-mail address. It can contain
a name and e-mail address in the legal forms for a RFC-822
'From:' header. It's not optional because cataloging systems
can use the e-mail portion of this field as a unique key
representing the author. A catalog might provide authors the
ability to store their GPG key, personal home page, and other
additional metadata *about the author*, and optionally the
ability to associate several e-mail addresses with the same
person. Author-related metadata fields are not covered by this
Example: 'Author-email: "C. Schultz" <email@example.com>'
A string selected from a short list of choices, specifying the
license covering the package. Some licenses result in the
software being freely redistributable, so packagers and
resellers can automatically know that they're free to
redistribute the software. Other licenses will require
a careful reading by a human to determine the software can be
repackaged and resold.
The choices are:
Artistic, BSD, DFSG, GNU PL, Lesser GNU PL, "MIT/X11",
Mozilla PL, "public domain", Python, Qt PL, Zope PL, unknown,
nocommercial, nosell, nosource, shareware, other
The definitions are:
Python Python 1.6 or higher license. Version 1.5.2 and
earlier are under the MIT/X11 license.
public domain Software is public domain, not copyrighted.
unknown Status is not known
nocommercial Free private use but commercial use not permitted
nosell Free use but distribution for profit by arrangement
nosource Freely distributable but no source code
shareware Payment is requested if software is used
other General category for other non-DFSG licenses
Some of these licenses can be interpreted to mean the software is
freely redistributable. The list of redistributable licenses is:
Artistic, BSD, DFSG, GNU PL, Lesser GNU PL, "MIT/X11",
Mozilla PL, "public domain", Python, Qt PL, Zope PL,
Note that being redistributable does not mean a package
qualifies as free software, 'nosource' and 'shareware' being
Example: 'License: MIT/X11'
This document has been placed in the public domain.